Binaural dereverberation

Room reverberation degrades the quality and intelligibility of speech and also reduces the performance of automatic speech-recognition systems. Hence, blind or semi-blind dereverberation methods have been developed, utilising single or multiple input channels. Dereverberation is also important for binaural applications in the context of digital hearing aids, binaural telephony and hands free devices. However, the development of binaural dereverberation solutions is not trivial. Apart from the challenging task of reducing reverberation without introducing audible artifacts, binaural dereverberation should also at least preserve the interaural arrival-time and amplitude differences of the signals at the two ears, as these represent relevant cues for sound-source localization. In this chapter, an overview of auditory perception and physical features of reverberation is given. Further, a literature review of dereverberation methods is presented, leading to the more recent binaural techniques. Two specific binaural-dereverberation methods will be considered in more detail, one of them relying on binaural coherence and the other one on utilizing spectral subtraction for suppressing late-reverberation effects. The results of performance tests on these methods will be presented, along with a discussion of suitable objective and perceptual evaluation methods.